RE: [PATCH]middle-end: Don't apply copysign optimization if target does not implement optab [PR112468]

[Tamar Christina <Tamar.Christina@arm.com>]

> -----Original Message-----
> From: Xi Ruoyao <xry111@xry111.site>
> Sent: Thursday, January 4, 2024 10:39 PM
> To: Palmer Dabbelt <palmer@dabbelt.com>; Tamar Christina
> <Tamar.Christina@arm.com>
> Cc: gcc-patches@gcc.gnu.org; nd <nd@arm.com>; rguenther@suse.de; Jeff Law
> <jlaw@ventanamicro.com>
> Subject: Re: [PATCH]middle-end: Don't apply copysign optimization if target does
> not implement optab [PR112468]
> 
> On Thu, 2024-01-04 at 14:32 -0800, Palmer Dabbelt wrote:
> > > +proc check_effective_target_ifn_copysign { } {
> > > +    return [check_cached_effective_target_indexed ifn_copysign {
> > > +      expr {
> > > +	 (([istarget i?86-*-*] || [istarget x86_64-*-*])
> > > +	   && [is-effective-target sse])
> > > +	 || ([istarget loongarch*-*-*] && [check_effective_target_loongarch_sx])
> 
> LoongArch has [scalar FP copysign][1] too.
> 
> [1]:https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-
> EN.html#_fscaleblogbcopysign_sd

Ok, so something like:

|| ([istarget loongarch*-*-*] && ([check_effective_target_loongarch_sx] ||  [check_effective_target_hard_float]))
?

> 
> > > +	 || ([istarget powerpc*-*-*]
> > > +	     && ![istarget powerpc-*-linux*paired*])
> > > +	 || [istarget alpha*-*-*]
> > > +	 || [istarget aarch64*-*-*]
> > > +	 || [is-effective-target arm_neon]
> > > +	 || ([istarget s390*-*-*]
> > > +	     && [check_effective_target_s390_vx])
> > > +	 || ([istarget riscv*-*-*]
> > > +	     && [check_effective_target_riscv_v])
> >
> > Unless I'm missing something, we have copysign in the scalar
> > floating-point ISAs as well.  So I think this should be
> >
> >       || ([istarget riscv*-*-*]
> >           && [check_effective_target_hard_float])
> 

Ah cool, will update it in next version. 

Thanks,
Tamar

> --
> Xi Ruoyao <xry111@xry111.site>
> School of Aerospace Science and Technology, Xidian University